Fix issue #5.

Prior to this commit there was a bug where puppet thought that every
installation of puppet was Puppet Enterprise. This fixes the logic so
that it should Do The Right Thing(tm) based on if you have
pe-puppet-enterprise-release installed or not.
Fix issue #7. Confine fact properly.

This should confine the fact to only happening on systems where yum
would make sense (like osfamily being RedHat).
If pper_installed is unef, fall through to FOSS error message

Prior to this commit, if you were on a non-yum using system you would
get a mesage saying you were not configuring puppetlabs_yum because you
had Puppet Enterprise installed. This simply wasn't true. Logic now
fixed to ensure if you're on a non-yum system it errors out with a
correct message.

This resolves and item brough up in issue #5.
Update module 0.0.14
Permit selection of YUM mirror
README.md: Clean up comment
Remove debugging code
Use str2bool instead of comparison with "false"
merge pper_installed.rb with upstream
merge pper_installed.rb with upstream
merge pper_installed.rb with upstream
merge
merge